Re: Sweet Mash -vs- Sour Mash

I have a copy from 1818 of a pair of recipes from a woman distiller in Kentucky. On one side is a recipe for sweet mash distiller's beer, the other, a recipe for sour mash. In this recipe sour mash was a process more similar to sourdough bread. In modern times the process has changed. By the time the mash has been distilled the yeast is dead and the spent beer is used only to recreate the best environment for the yeast strain to grow in by helping to match the ph of the mash. I suspect that on a start up situation most distillers will use some other acid in their mash to get the proper ph thus making it a "sour mash". I know Chris Morris stated at L&amp;G that that is what they do for the whiskey they are distilling for Woodford Reserve.

Re: Sweet Mash -vs- Sour Mash

Mike, that is very interesting. Can you elaborate on the woman distiller's concept of sour mash? Do you mean she collected yeast from the ferment and added it to the next mash to ferment the next batch of beer before it was distilled?

If that is correct that is different from the modern understanding as you said.

I looked again in Byrn's Practical Distilling text of 1875. (This book in its reprint form was mentioned on this board about a year ago, it can be purchased from Glenn Raudins, the reprinter, at www.raudins.com). The book is mainly concerned with distilling proper. But Byrn does discuss mashing, and fermentation in a number of passages. Twice when talking about French methods, he says spent wash is taken from the still and mixed (always, he says) with water. Then it is added to a mash to "cool and dilute" it. He says this is done because there are unconverted starches which still can be converted and even some sugars that (despite his statement elsewhere in the book that these are unfermentable) can be fermented to make more alcohol. He says also this process can only be used 3 -5 times successively because the spent wash becomes too acid, he actually says, "sour", and fermentation will not occur after such number of applications. This suggests he meant the distiller must ferment completely anew (no backset) after about 5 sourmashes.

A separate point he does not address is whether yeast is collected from the fermented mix of backset and mashed grain to add to the next ferment. I assume (but don't know for sure) that yeast must today be collected in this manner, as in straight brewing, to add to the next mash (whether it has backset or no and one thing is sure, that backset will have no live yeast in it).

Can a brand new yeast be prepared from a pure culture for each mash? Is that feasible given the amount of yeast needed in large scale mashing? I don't know the answer to that one but have always assumed the distillers would collect yeast from a previous mash, store it and use it for the next one until they need to refresh it for reasons earlier discussed.

Re: Sweet Mash -vs- Sour Mash

Gary,
Yeast is always added to the mash. Some use bag yeast, other raise their own from a culture, but they always add yeast. The spent beer is used only to create the best conditions for that yeast to grow. The yeast in the spent beer is dead by the time it is added to the mash. This means that if yeast was not added, you would be depending upon wild yeast from the air for your fermentation and there is no telling what type of product you would end up with in your beer.

I would also find it hard to believe that one distiller would use spent beer from another distillery to sour their mash because of the different yeast strains and more importantly different grains or amount of grains could change the flavor of the product. Someone mentioned Maker's Mark using Heavan Hill spent beer for their start up, yet until recently, Heaven Hill did not have a wheated bourbon, so rye would be in that spent beer. What would that do to their flavor? I don't know, but I am willing to bet Maker's Mark does not want to find out the hard way if it was bad for their flavor profile.
Mike Veach

Re: Sweet Mash -vs- Sour Mash

Betty Jo,
I stand corrected. It does surprise me though that they would do it that way, but maybe they are trying to keep the use of chemicals down to a minimum. One of the things I admire most about Heaven Hill is the fact they changed the Bernheim distillery around to use jug yeast instead of the bag yeast U.D. was using. I also assume they are not using the enzyme to suppliment the malted barley in the mash. I prefer to see the whiskey made in more traditional methods, so good for Maker's Mark and Heaven Hill for helping them out.

Has Heaven Hill always done this for Maker's Mark, or is it something that just started doing? Was the slop (if you prefer) from some wheated recipe bourbon or a rye? If it was wheated then the chance of changing the taste is reduced.

Re: Sweet Mash -vs- Sour Mash

You can think of sour mash as an additional step. If sour mash (i.e., the use of set back) isn't done, then it's sweet mash. As Mike said, everyone adds fresh yeast, whether it's a monoculture yeast from bags or a propogated wild yeast from jugs. I have been told that with modern process controls, sour mash isn't really necessary, but everyone still does it because it is the tradition.

Re: Sweet Mash -vs- Sour Mash

I realise there has to be fresh yeast, as for any ferment except where a source is available spontaneously, e.g. from grapeskins in winemaking. Spent wash could not have contributed live yeast cells since the distillation heat would have killed them. I was wondering where the yeast for the successive mashes came from, ie. was it collected from previous ferments (before the boils) or was it made anew for each batch from a pure culture? I think Mike and you answered that, it either is propagated in jugs from previous brews (and thus is wild to an extent but monitored for cleanliness and potency) or is made fresh each time (I read elsewhere) from an agar slant in the distillery laboratory. The bag yeast method sounds like a commercial source of yeast which is a variation on the former method.

If there was a brewery nearby, one could always buy yeast from them, and Byrn speaks of English and Scottish distillers using large amounts of "fresh porter yeast" for this purpose. I should add too he makes a reference at one point to the felt need not to collect yeast from each ferment, that it was left in because it was felt more alcohol was produced (i.e., presumably the mash was turbid from yeast when distilled). This would make sense where they could be assured of buying fresh porter or ale yeast from the many breweries in Britain.

Based on what Byrn says about French methods (1875), sour mash related always to acidity levels and secondarily to an additional ("free") source of fermentable sugar via unfermented sugars or unconverted starches.

I always understood too the jug method of keeping yeast going is a sweet mash no less than any other way of obtaining a yeast source where no backset is used. The use of jug yeast is not (as far as I can glean) related to the term "sour mash bourbon", at least not how it has been used for over 100 years. Mike said the early 1800's woman distiller used the term sour mash bourbon more in the sense connected to sourdough bread, and it would be interesting to learn more about what she meant by the term sour, and sweet, mashes.